Field of the Invention
The disclosure relates to a flowmeter, an insulation deterioration diagnosis system, and an insulation deterioration diagnosis method.
Priority is claimed on Japanese Patent Application No. 2014-143174, filed Jul. 11, 2014, the contents of which are incorporated herein by reference.
Description of Related Art
A flowmeter is widely used for measuring flow quantity of liquid, gas, and other fluids. Various types of flowmeters are developed in accordance with properties and uses of the fluid which is a measurement target. An electromagnetic flowmeter is an example of these flowmeters. The electromagnetic flowmeter detects an electromotive force generated by applying a magnetic field to the fluid (an electromotive force proportional to flow velocity) so that the electromagnetic flowmeter measures flow quantity of the fluid.
The electromagnetic flowmeter is mounted on a pipe in which the fluid flows. The electromagnetic flowmeter is equipped with a detector which has an exciting coil and detecting electrodes. The exciting coil generates a magnetic field which is applied to the fluid. The detecting electrodes detect the electromotive force generated in the fluid. In a case that an insulation of the exciting coil in the detector deteriorates, a magnitude of the magnetic field is changed. In this case, even if the flow quantity of the fluid is not changed, the electromotive force generated in the fluid is changed. For the reason, the electromagnetic flowmeter measures improper flow quantity. So as to prevent from measuring improper flow quantity, the electromagnetic flowmeter performs an insulation deterioration diagnosis of the exciting coil.
In Japanese Unexamined Patent Application Publication No. 2008-020364, Japanese Unexamined Patent Application Publication No. 2007-240231, Japanese Unexamined Patent Application Publication No. 2007-225487, Japanese Unexamined Patent Application Publication No. 2005-207984, Japanese Unexamined Patent Application Publication No. 2003-177040, Japanese Unexamined Patent Application Publication No. 2003-106879, Japanese Unexamined Patent Application Publication No. 2003-097986, and Japanese Unexamined Patent Application Publication No. 2002-195861, an electromagnetic flowmeter which has a function of an insulation deterioration diagnosis of an exciting coil is disclosed. For example, in Japanese Unexamined Patent Application Publication No. 2008-020364, an electromagnetic flowmeter which diagnoses insulation deterioration in accordance with a change in inductance of an exciting coil is disclosed. For example, in Japanese Unexamined Patent Application Publication No. 2005-207984, so as to omit a dedicated signal line for the insulation deterioration diagnosis, an electromagnetic flowmeter, which superimposes a signal for the insulation deterioration diagnosis with a measurement signal of the flow quantity, is disclosed.
As described above, the detector of the electromagnetic flowmeter is mounted on the pipe in which the fluid flows. For the reason, in a case of exchanging or changing the detector, there is a need to empty the pipe by stopping the flow of the fluid in the pipe. Therefore, it is difficult to exchange or change the detector easily. In a case that the flow of the fluid is stopped so as to exchange or change the detector, there is a possibility that a large opportunity loss occurs in a plant and a factory.
Because it is difficult to exchange and change the detector easily, for example, there is a problem that it is difficult to add a configuration necessary for the insulation deterioration diagnosis in the detector mounted on the pipe, or it is difficult that the detector mounted on the pipe is exchanged to another detector having a configuration necessary for the insulation deterioration diagnosis. The problem is not limited to the electromagnetic flowmeter, and the problem may occur in other flowmeters (for example, a Coriolis-type mass flowmeter required to excite a tube in which fluid flows).